Pneumonia PDF

Pneumonia  definition Treatment Pathology Learning Outcome Diagnosis Pathogenesis Classification  Definition Definition: It is acute inflammation of the lung parenchyma. The cause may...

Pneumonia  definition Treatment Pathology Learning Outcome Diagnosis Pathogenesis Classification  Definition Definition: It is acute inflammation of the lung parenchyma. The cause may be infectious or non infectious. It may be acquired in the community (CAP) or in the hospital (HAP-VAP). Community Acquired Pneumonia (CAP): Pneumonia in a patient not hospitalized or less than 48 hours from hospital admission  Pathology (Stages of Pneumonia) 1- Stage of Congestion :presence of a proteinaceous exudate and often of bacteria in the alveoli This phase is rarely evident in clinical or autopsy specimens because it is so rapidly followed by a red hepatization 2- Red hepatization he alveoli fill with red blood cells, neutrophils, fibrin, and bacteria, causing the affected lung tissue to become more solid and firm, resembling the texture of the liver (hence the term "hepatization"). 3- Gray hepatization : Red blood cells within the alveoli begin to break down, and the color of the lung changes from red to gray. Neutrophils, macrophages, and fibrin continue to fill the alveoli, while the bacteria are starting to be controlled or destroyed by the immune response. 4. Resolution :The infection is cleared by the immune system, and the alveolar exudate (fluid and debris) is gradually reabsorbed or coughed up. The lung tissue begins to return to its normal state  Routes of organism entry into the lungs 1. Inhalation of air born droplets 2. Aspiration of organisms from the oropharynx: 3. Hematogenous spread from infected sites outside the lungs: sepsis. 4. Direct spread: adjacent abscess.  Classification of pneumonia a) Infectious 1.Etiological b) Non Infectiou a) Lobar 2.Distribution b) Bronchopneumonia c) Interstitial a) Community-Acquired Pneumonia (CAP) 3.Clinical b) Hospital-Acquired Pneumonia (HAP) c) Ventilator-Associated Pneumonia (VAP) What is the commonest cause of pneumonia? Streptococcus pneumoniae 35% Distribution Bronchopneumonia Lobar Interstitial  CLINICAL 1. Community-Acquired Pneumonia (CAP): Occurs in individuals who are not hospitalized or living in a long- term care facility. It is the most common type and is often caused by Streptococcus pneumoniae or respiratory viruses. 2. Hospital-Acquired Pneumonia (HAP)Also known as nosocomial pneumonia, it occurs 48 hours or more after hospital admission Common pathogens include Pseudomonas aeruginosa and Methicillin-resistant Staphylococcus aureus (MRSA). 3.Ventilator-Associated Pneumonia (VAP): A type of HAP that develops in patients on mechanical ventilation for more than 48 hours. VAP is often caused by multidrug-resistant organisms.  Atypical pneumonia Character by :  Non-respiratory symptoms are dominating, e.g. headache, confusion, loss of mental clarity, abdominal pain, diarrhea.  Absence of organism by culture or Gram stain in the sputum samples may suggest infection with atypical organisms  The usual auscultatory findings of consolidation may be absent or difficult to detect making a chest x-ray or even CT scan is essential for diagnosis  General symptom 1. Fever and Chills 2. Fatigue and Weakness 3. Muscle aches: Sometimes pneumonia can cause body or muscle aches, especially if it's caused by a viral infection like influenza. 4. Confusion or Altered Mental Status Especially in older adults, pneumonia may cause confusion or changes in mental awareness. 5. Gastrointestinal Symptoms ○ Nausea or vomiting: These symptoms can accompany fever ○ Diarrhea: Sometimes associated with viral causes of pneumonia. 6. Cyanosis In severe cases 7. Low Blood Pressure and Increased Heart Rate In severe cases, pneumonia can cause low blood pressure (hypotension) and an increased heart rate (tachycardia) as the body struggles to maintain oxygen delivery to tissues.  Respiratory Symptoms 1. Cough: May produce green, yellow, or even bloody mucus 2. Shortness of breath: Difficulty breathing, even while at rest or with minimal activity. 3. Chest pain: Sharp or stabbing pain that worsens with deep breathing or coughing. 4. Rapid or shallow breathing: Breathing faster than usual due to difficulty getting enough oxygen.  General signs of pneumonia 1.Tachypnea and tachycardia 2. Temperature: 38.5 - 39.5oC, with or without rigors. 3. Cyanosis in severe cases  Local signs of pneumonia Inspection : Diminished respiratory movement of the affected side. Percussion : dullness Auscultation : Crepitations The investigation of pneumonia A. Laboratory Tests 1. Complete Blood Count (CBC): ○ Elevated white blood cells (leukocytosis) indicate infection. ○ Neutrophilia suggests bacterial infection, while lymphocytosis may suggest a viral cause. 2.Blood Cultures: ○ Taken to detect the presence of bacteria in the bloodstream, especially in severe pneumonia cases. 3.Sputum Analysis:  Gram Stain: Helps identify the type of bacteria present in the sputum.  Culture and Sensitivity: Determines the specific bacteria and their antibiotic sensitivities.  AFB Staining: For suspected tuberculosis, acid-fast bacilli (AFB) staining can help detect Mycobacterium tuberculosis. 4.Viral PCR Tests: Detects specific viral causes of pneumonia, such as influenza, respiratory syncytial virus (RSV), or SARS- CoV-2 (COVID-19). 5.Urine Antigen Tests: Useful for detecting specific bacterial pathogens like: ○ Legionella pneumophila (Legionnaires' disease). 6. Procalcitonin/CRP Levels: Biomarkers that can help differentiate between bacterial and viral infections, as they tend to rise in bacterial infections.  B. Imaging 1. Chest X-ray: The most common initial imaging test used to diagnose pneumonia. Findings may include: ○ Lobar consolidation (in lobar pneumonia). ○ Patchy infiltrates (in bronchopneumonia). ○ Interstitial markings (in viral or atypical pneumonia). Helps differentiate pneumonia from other conditions like heart failure or pulmonary embolism.  atypical pneumonia bronchopneumonia lobar pneumonia Treatment pneumonia 1. Supportive treatment 1. Fluid and electrolyte replacement 2. Proper nutrition: Enteral or total parenteral nutrition in severe pneumonias in whom mechanical ventilation and shock are likely to be prolonged. 3. Inotropic agents as norepinephrine and epinephrine in shocked patients. 4. Respiratory support: a- Oxygen inhalation. b- Mechanical ventilation if: - PaO2 < 60 mmHg. - Rising or PaCO2 > 50mmHg. 5. Pleuritic pain: simple analgesics 2. Antibiotic Therapy (for Bacterial Pneumonia) Outpatient treatment: ○ First-line antibiotics include a macrolide (e.g., azithromycin or clarithromycin) or a tetracycline (e.g., doxycycline). ○ For patients with comorbidities, fluoroquinolones (e.g., levofloxacin) or a combination of a beta-lactam (e.g., amoxicillin/clavulanate) and a macrolide may be used. Inpatient treatment: ○ Broad-spectrum antibiotics like ceftriaxone, cefotaxime, or fluoroquinolones (e.g., moxifloxacin) are typically used. For ICU patients,: a combination of a beta-lactam (e.g., ceftriaxone) and a macrolide (e.g., azithromycin) or fluoroquinolone is recommended.  3. Antiviral Therapy (for Viral Pneumonia) Influenza Virus:Antiviral medications like oseltamivir (Tamiflu) is recommended if the infection is due to the flu virus, especially if started within 48 hours of symptom onset. COVID-19 (SARS-CoV-2):Treatment includes antiviral medications like remdesivir in moderate to severe cases, along with corticosteroids (e.g., dexamethasone) to reduce inflammation in severe cases.  Duration of therapy is 5 days and might extend to 7 days  Make sure all patients are improving on therapy and are afebrile for at least 2 days before stopping antibiotics.  If a sputum sample was sent for sensitivity testing → review the choice of antibiotic(s) when results available, → consider changing the antibiotic(s) using a narrower spectrum antibiotic if appropriate